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Início - ICHMT DL Ano atual Arquivos Comitê executivo Centro Internacional para Transferência de Calor e Massa

MEASUREMENT OF TWO-PHASE INTERFACIAL DRAG IN STRATIFIED FLOW WITH PULSED LASER VELOCIMETRY

DOI: 10.1615/ICHMT.1992.IntSympImgTranspProc.270
pages 283-294

Yassin A. Hassan
Department of Nuclear Engineering, Texas A&M University, College Station, TX 77843, USA

Thomas K . Blanchat
Fire Science & Technologies, Sandia National Laboratories, Albuquerque, NM

Resumo

Investigation of a two-phase, horizontal, stratified, flow regime is being performed with pulsed laser velocimetry to determine the interface drag force due to the relative motion between the two fluids at the interface [8, 9]. This technique is a full-field, two-dimensional, noninvasive flow visualization technique [1]. The main advantage of PLV techniques is that simultaneous qualitative and quantitative full-field maps are produced of fluid flow parameters (such as velocity and shear stress) over extended areas. PLV data is acquired by shaping a pulsed laser beam into a thin sheet of light, and passing this sheet of light into seeded fluid. The light scattered from the reflective tracer particles is then imaged with a digital camera. By synchronizing camera frame acquisition with the laser pulse frequency, a time sequence of the fluid motion can be captured. The data is analyzed with imaging system hardware and a series of new image processing and tracking analysis software developed for flow experiments.
Interphase drag plays an important role in two-phase fluid regimes. Study of two-phase (and similarly two-component) flow regimes is necessary to properly understand and model complex fluid flows. Many computer codes which predict two-phase fluid flow must determine interphase drag force. Typically, a drag coefficient correlation is used which was empirically determined. One such code is RELAP5/MOD2 [13]. This code is used extensively in the nuclear power industry to simulate a wide range of steady-state, transient, and accident conditions in pressurized water reactors. Some researchers have found that two-phase thermal-hydraulic codes do not model two-phase flow very well [2, 7]. Part of this deficiency has been attributed to an over-prediction of the drag force, which may be caused by an inappropriate drag coefficient [12].

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